Electric switch.



C. H. MILLER.

ELECTRIC SWITCH APPLIQATION FILED ocnzs. 1913.

Patented Apr. 30,1918.

UNITED STATES oFFIoE;

CHARLE H. MILLER, or MILWAUKEE, wIsCoNsrN, fi-ssreivon To o i r nngIrAi/INIER MFG. 00., or MILWAUKEE, wIsCoNSIN, A CORPORATION or WISCONSIN.

ELECTRIC weets.

Specification of Letters Patent;

Patented Apr. 30, 1918.

Application filed Octet-e128, 1913. Serial No. 797,888.

To all whom it may concern Be it known that I, CHARLES H. MILLER, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee-and tate of Wisconsin, have invented new and useful Improvements in Electric Switches, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawing, forming a part of this specification.

My invention relates to improvements in electric switches.

Switches embodying my invention may be advantageously employed for various different purposes and particularly for automatic motor starters wherein progressive operation of the accelerating switches and automatic throttling thereof is desired.

In order to disclose the nature and objects of my invention, I shall now describe the embodiment thereof illustrated in the accompanying drawing, it being understood that my invention might be embodied in other forms and employed in different relations.

The views in the drawing are as follows:

Figure 1 is a side elevation of the switch;

and,

Fig. 2 is a diagrammatic view of a motor controller employing a number of said switches.

The switch comprises the following parts of conventional form, namely, a pivoted arm 1 having a main contact 2 and a pivoted arcing contact 3, cooperating stationary contacts & and 5 and an operating magnet 6. The arm 1 and the magnet 6 are supported by a magnet frame 7 secured to a suitable supporting panel 8 while the contacts 1 and 5 are carried by a suitable holder 9 also secured to the panel 8. In operation the magnet 6 attracts the arm 1 to first move the arcing contact 3 into engagement with the contact 5 and then move the main contact 2 into engagement with contact 4. Thus the arm 1 has a continued movement after closure of circuit by its arcing contact.

Referring now to the additional features of the switch, the same include auxiliary cooperating contacts 10 and 11. The contact 10 is carried by an extension 12 of the arm 1 and is in electrical connection with said arm. The contact 11 constitutes the armature of an electromagnet 13 supported in a substantially U-shaped magnetic frame 14 secured to the base 8. The contact 11 has a pivotal bearing 15 on the extremity of one of the upright members of the magnet frame. 14, while a spring 16 connecting the outer end thereof to the magnet frame biases the said Contact upwardly against a stop 17 When the contact 11 rests against the stop 17 attraction and release of the main switch arm 1 moves the Contact 10 into and out of engagement therewith, while the magnet 13 when energized to overcome the tension of spring 16, serves to attract the contact 11 out of reach of the contact 10. One end of the spring- 16 is connected to the magnet frame 14 by an adjustable tension device 18 whereby the attraction of the contact 11 may be limited to any predetermined minimum pull of the magnet 13;

The switch arm 1 and upper terminal of the magnet 13 are electrically connected to a common terminal 20 while the lower terminal of the magnet 13 is connected to a terminal 21. The frame 14 of the magnet 13 is connected to a terminal 22 and said frame constitutes'a conducting path from said terminal to contact 11;

Referringxnow to Fig. 2 the controller illustrated therein employes two of the aforesaid Switches designated as a and b and a switch 0 similar to the switch above described but without the auxiliary contacts. These switches control the continuityof the circuit of a motor M and effect automatic acceleration of the motor by exclusion of resistances 1' and 1". They are controlled by a manual switch 23. The auxiliary contacts of switches a and 6 function to insure progressive operation of the switches and to throttle switches b and 0 under abnormal electrical conditions.

The operation of the controller is as follows: Switch 23, when closed, completes circuit from line L by conductor 24 through the operating magnet 6 of switch a by con ductor 25 to line L. Switch a thereupon responds, completing the motor circuit from line L by conductor 26 through the coil 13 of switch a, by conductor 27 through the arm 1 of said switch, by conductor 28 through the resistances 1' and r in series and thence through the motor armature and field winding to line L. The motor is thus started with both resistances in series therewith. 7

Switch a in closing also moves its auxiliary contact 10 into engagement with its auxiliary contact 11 and in so doing coinpletes circuit from switch arm 1 through said auxiliary contacts by conductor 29 through the ope 'ating magnet 6 of switch 7) to conductor 25 and thence to line L". However, upon initial closure of circuit by switch a, that is through its arcing contacts, its winding 13 is included in series with the'motor circuit, whereby it the surge of current through the motor exceeds certain values de pending upon the tension adjustment of contact 11, said winding attracts contact 11 out of reach of the contact 10. Further, this at traction occurs before the switch arm 1 is fully attracted and accordingly before the auxiliary contact 10 reaches the normal position of the contact 11. Such an attraction of the contact 11 obviously prevents completion of the energizing circuit of: switch 6 until the motor current is reduced to a degree suflicient to eii'ect release of the contact 11. Vhen, however, the contact 11 is released, the spring 16 moves the same into engage ment with contact 10, thereby energizing switch 6 through the circuit above de scribed.

Switch Z) in closing short-circuits the resistance 1- and the winding 13 of switch a. The motor circuit then extends from line L by conductor 26 through the winding 13 of switch I) by conductor 30 through switch I) and thence directly through resistance r and the motor.

Switch 6 in closing also functions in the same manner as above described in connec tion with switch a to: energize switch 0 subject to retardation by response of its magnet 13.

Thus the switches accomplish automatic acceleration of the motor in a gradual manner and automatically protect the motor against excessive surges of current. Further, they accomplish these results with but a single set of auxiliary contacts for each switch and with exceedingly simple circuit connections.

While the switch shown in Fig. 1 has been herein employed for motor controllers, it is obvious that the same is susceptible of use in other relations.

What I claim as new and desire to secure by Letters Patent is:

1. The combination, with an electric switch provided with successively engaging arcing and main contacts and an auxiliary contact, of a contact to be engaged by said auxiliary contact upon full movement of said switch, and an. electromagnet connected in circuit by said arcing contact of said switch to attract said last-mentioned contact out of reach of said auxiliary contact.

2. The combination, with an electric switch provided with successively engaging arcing contacts andmain contacts, 01" a pair of cooperating auxiliary contacts, one mechanically actuated by said switch and an electromagnet for controlling the position of the other of said auxiliary contacts, said magnet being connected in circuit by the arcing contacts of said switch and piorto the full movement of the auxiliary contact actuated by said switch.

3. The combination, with an electric switch having an auxiliary contact mechanically actuated thereby, of a cooperating contact biased to a position to be engaged by said auxiliary contact upon full movement of said switch, an electromagnet connected in circuit by said switch prior to full operation thereof, to attract said biased contact under certain electrical conditions and adjustable means for determining the electrical conditions under which said electromagnet is effective. r

In witness whereof, I have hereunto sul scribed my name in the presence of two witnesses.

CHARLES H. MILLER. l Vitnesses F. H. HUBBARD,

L. F. WATSON.

Copies 01,1311; patent may be obtained for five .cents each, by addressing the Commissioner of Patents,

' Washington, D. G. 

